The filament of an electric bulb behaves nearly as a blackbody

PHYSICS · Multi-part · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter

Problem

The filament of an electric bulb behaves nearly as a blackbody. When operated at its rated voltage it attains a steady temperature of

2900\,\text{K}

. In this state the wavelength at which the emitted intensity is maximum is denoted by

\lambda_1

. The supply voltage is then increased so that the new peak wavelength becomes

0.70\,\lambda_1

. (Wien's constant

b = 2.9 \times 10^{-3}\,\text{m K}

.) (i) Determine the value of

\lambda_1

. (ii) Find the new temperature reached by the filament. (iii) Calculate the percentage rise in temperature of the filament.